DESCRIPTION (provided by candidate): Attentional bias toward addiction-related material is a common feature of substance use disorders (SUDs), and one which can predict relapse. Despite its clinical significance, the neural mechanisms of such attentional bias remain largely unknown. The bias has been found in a wide variety of substance dependent individuals including in smokers. The broad aim of this proposal is to make a detailed characterization of nicotine addiction-related attentional bias at the behavioral and neurobiological level, and to determine whether this cognitive correlate of addiction is sensitive to a specific pharmacological treatment. This project aims to: (1) determine whether cigarette cues preferentially capture and/or hold attention in smokers, (2) determine the neurobiological basis of attentional bias in smokers using functional MRI, and (3) test the efficacy of opioid receptor blockade in reducing attentional bias toward drug cues. Participants will consist of active smokers and non-smoking control participants. A dot-probe paradigm will be used to assess the quick capture of attention by drug cues. It is expected that, for smokers and not controls, smoking-related stimuli will preferentially capture attention. An attentional blink task will be used to measure attentional hold. By using both tasks within subjects, we will determine whether drug-cue effects on these two aspects of attention, capture and hold, are independent. These same two paradigms will be used during fMRI scanning to explore the neural bases of the drug-cue attentional bias in smokers. We will also test whether naltrexone, an opioid receptor antagonist under investigation for smoking cessation, reduces addiction-related attentional bias, as opioid antagonists reduce nicotine cue-induced reinstatement of drug seeking in rodents and impair selective attention in human subjects. The proposed studies will make significant progress toward identifying the neurobiological correlates of smoking-related attentional bias, which may also generalize to other forms of SUDs. Attentional bias toward addiction-related material is an important phenomenon to study, as the magnitude of such bias in abstinent drug dependent individuals predicts their likelihood of relapse. A better understanding of the neurobiological underpinnings of addiction-related attentional bias and whether it is impacted by the addiction medication naltrexone, could lead to better treatment plans and prolonged abstinence for those struggling to abstain from nicotine and possibly other drugs of abuse.